Power Flow Findings
Id like to add some experience to your report on Power Flow exhaust system article in the February 2009 issue. We installed a Power Flow exhaust on our 1976 Cessna 172M about eight years ago. Its been long enough that I cant provide any reliable performance improvement numbers, but what I read in your article is about what we experienced. A significant advantage is the ability to lean more with our Lycoming O-320-E2D. I advise all our pilots to lean aggressively. We installed an
engine monitor and discovered that the only engine or flight mode that causes heat problems is high-altitude Vy climb, when the lower density of the air doesnt provide adequate cooling below 70 knots or so. This is at altitudes above the stock service ceiling of the 172.
Your article failed to mention a significant advantage of the system that weve discovered–an approximately 3000-foot increase in the service ceiling. The airplane is now just capable of the flight levels in winter. I intend to get charts one of these days and try it to see what kind of comments I can get on the radio.
I have frequently taken advantage of the wintertime jet stream in our Skyhawk with a portable oxygen system. I have flown from Ames, Iowa back to College Park, Maryland, 800 miles in 5:25 using 25 gallons of gas. I had a 70 knot tailwind at 17,000 feet. Two years ago, the collector pipe cracked and we replaced the system with a more recent version. Power Flow encouraged us to check the prop balance, which we discovered was causing a lot of vibration.
When we replaced the system, we went with the short stack version, but discovered it did not provide the altitude performance, so we changed it back out for the resonator pipe.
We feel the altitude performance is we’ll worth the added maintenance effort of removing the pipe to drop the lower cowl.
Phil Railsback,
Maintenance Officer,
Free State Flying Club, Inc.
Reader Plates
I was interested in what you said about Reader Plates in the March 2009 issue, since I have been using this system. Mostly, it was right on, but you say you have to scale up to see the details, which changes orientation.